From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754628AbcEYMQa (ORCPT ); Wed, 25 May 2016 08:16:30 -0400 Received: from webbox1416.server-home.net ([77.236.96.61]:53333 "EHLO webbox1416.server-home.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753446AbcEYMQ3 (ORCPT ); Wed, 25 May 2016 08:16:29 -0400 From: Alexander Stein To: Meng Yi Cc: Stefan Agner , "dri-devel@lists.freedesktop.org" , David Airlie , "airlied@redhat.com" , "linux-kernel@vger.kernel.org" , Mark Brown Subject: Re: fsl-dcu not works on latest "drm-next" Date: Wed, 25 May 2016 14:16:20 +0200 Message-ID: <8051435.bV5T0CxpSc@ws-stein> User-Agent: KMail/4.14.10 (Linux/4.4.6-gentoo; KDE/4.14.16; x86_64; ; ) In-Reply-To: References: <2162860.ovvuqaWfeW@ws-stein> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday 25 May 2016 10:25:29, Meng Yi wrote: > Hi Alexander, > Thanks for your reply. > > > Commit d761701c55a99598477f3cb25c03d939a7711e74 only has one child > > commit in my repo. Both touch only i915 related things. Please do a proper > > bisect and name the offending commit. On which commit you got that > > backtrace BTW? > > From your backtrace I can't see anything related to regmap. > > It is weird that using bisect, for the commit log is not linear. > I mean a newer date commit may be merged before an older date commit, when > jump to that older date commit, the newer one will be lost, even though it > is merged before older one. So, I think it's difficult to use git bisect. > " d761701c55a99598477f3cb25c03d939a7711e74 " is just an older one, I mean > between this commit and the next commit, maybe lots of commits are lost. > So, it looks like this commit have nothing to do with the problem. Why are commits lost? The order of commit dates is not straightforward, yes, but that's not a problem at all. > According to the backtrace, looks like the vblank interrupt is not happen or > handled. Then I found the irq is installed successfully, so the problem > seems like the vblank irq is not properly setup. And here is the point , > irq initia, irq handler and timing control code are using regmap. >>From your backtrace I guess wait_event_timeout is called in some atomic context (might_sleep(); is called inside wait_event_timeout). This has nothing to do with regmap. > I read out the value of relevant register using "CodeWarrior TAP", find that > endianness is not right. > > Then I changed endianness of the value to be written that using " > regmap_write" . It works. But "regmap_update_bits" still have the problem. > > I had checked log of regmap, and didn't find which commit caused that. The inital problem came up with 922a9f936e40001f9b921379aab90047d5990923 ("regmap: mmio: Convert to regmap_bus and fix accessor usage"). The commits 9f9f8b863ad130ec0c25f378bdbad64ba71291de, 4f7d6dd4df8b388e2056c89b528254cdd79dea2a and 0dbdb76c0ca8e7caf27c9a210f64c4359e2974a4 tried to fix that. With those I could successfully probe DCU. Best regards, Alexander